How to heat an icebox of a bathroom

malex

Here is one heating situation that the dead men did not calculate correctly unless it worked differently way back when: I have a small half bath on the first floor that sits outside the footprint of the basement so there is just a crawl space under it. Additionally, it is "built into" the un-conditioned garage (north facing), which means that 5 out of 6 sides of the 'box' meets cold air. We had the walls injected with cellulose but it is not doing much. The bath is heated with a small three section rad, which seems properly sized for the small bath and gets hot alright, but it cools off immediately and only provides heat during cycles. As the living room where the tstat is located stays nice and toasty without calling for heat too often, the bathroom stays cold basically all the time (at least when you need to use it).



Is there any way to remedy this with steam or what is the best way to heat this space? Putting in a larger rad does not seem like a viable option as it will cool off just as fast. I have one room already heated by a hot water loop off the steam boiler so it would be possible to ad another zone I assume with a manifold. An electric heater on the wall would be another possibility. Radiant is likely out of the question because of the small floor area (about 5 sqft) and also I don't think anyone would want to crawl in under there to do it or would charge accordingly.

Steamhead

That was probably the pantry when it was built

and was not expected to stay warm in the winter. When electric refrigerators became standard, it was common to change these pantries to bathrooms.



The room probably leaks air like a sieve. Aside from insulating the walls and floor (and ceiling if there is not a heated room above) and caulking all the cracks you can find, you also want to insulate and seal the crawlspace walls. The further you can keep the cold air from the room, the warmer it will be.



If the steam pipe to the rad is not insulated, insulate it too.

Long Beach Ed

Heating Cold Bath

When rooms on the same system have entirely different heat loss characteristics, it's very difficult to get consistent heating. 



Your first exercise should be a heat loss calculation of the bathroom to assure that the radiator is not undersized. 



If the radiator is sized properly, the way to solve this problem is to insulate the room  so that it looses heat at a similar rate to the rest of the building.  Then you'd do a heat loss calculation and size a radiator properly to that newly insulated room.  



If it's not practical to improve the envelope, you'll have to consider another heat source, which is a major addition.  We've served problem zones such as this two ways. 



You can install an independent wall-mounted vented gas heater if you have gas in the building.  This would have its own thermostat and would work completely independent of the steam system.   



Or you can install a hot water loop from the steam boiler with a hot water radiator on its own zone.  That too will solve your problem. 



Those are your choices.  Insulation is always the least costly.

crash2009

Which rad is in the ice box?

4 or 8

Jamie Hall

A place I lived...

for a while the bathroom was really cold in the winter... it was also a 40 foot hike outside the back door...



This is one application where a good wall mounted gas heater -- vented -- if you have gas might work very well indeed.  It is also, however, an excellent place for a wall mounted electric heater (yeah, I know, heresy).  You wouldn't need a big one -- 1500 watts should do it nicely (you can check the heat loss, but I'll bet that would be enough) and it has the advantage of being really simple to install!

malex

This is rad 5

on the diagram in Crash's post. The rad gets hot properly along with the other ones but cools off real quick. Heat loss is obviously much greater than the rest of the house but we have done as much as possiple as far as insulation goes - cellulose blown into 3 walls and ceiling and new double pane window so there is really not much left to do. The floor could use some more probably but it is really tricky to get to this area of the crawlspace.



A larger rad would really crowd this tiny bathroom and you would probably burn your knee once seated... And I feel you would probably just get the room hotter while the boiler is running but it would cool off just as quick off cycle.



An electric wall hung heater sounds like the way to go, unless it will ruin me to run it more often that the steam comes on. Maybe on a timer (but how do one anticipate the need for bathroom breaks?)

kcopp

if it heats up....

that is not the problem. Your envelope is. You must seal it up. I would start w/ foam underneath and seal up the walls around the crawlspace. Otherwise all that heat you are paying for is out the window or floor.... seems a waste to me.

malex

Would you recommend

rigid foam under the floor boards and on the crawl space walls with expanding foam to seal the seams or does it need to be expanding foam all over?



I'm also going to add rigid foam on the outside of the box from the garage side. Hopefully this will help some.

David Nadle

Measure once

Get yourself an infrared thermometer with a laser pointer and aim it all around the room. These thermometers can be had for $50 or so. I think every homeowner should have one. Wait for a cold and windy day to do this. I think you will find cold spots where air is leaking out. Check every gap, including the trim around the new window, and especially along the top of doors and windows. Apply caulk wherever you find a cold spot. In fact, do the whole house.



It's possible the crawlspace is vented and therefore very cold in winter. There are ways to insulate a crawlspace properly so that the vents can be sealed. Here is one example:

http://www.certainteed.com/resources/30211292.pdf

BobC

Thermometer went below -40 several times

Did yours look like this and was it the deluxe two seater model?



That was about 80 ft from my NCO hut that was on top of a mountain in S Korea, I lived up there in 1969 for the whole year with 5 other GI's. The only heat in that convenience was a bare 100w light bulb hanging from the ceiling.



i agree that a wall mounted electric heater might be the easiest way out of this problem.



Bob

AaronH

Try an electric wall heater

They're less than $150 and easy to install. Most have a built-in thermostat. I just put in a surface-mount Steibel Eltron 1500w unit that also has a timer, which is great for a 20-min boost during a morning shower.

kcopp

The ridgid....

board is your best bet and seal up all the seams and voids w/ canned spray foam. ..aka great stuff.  You could do the whole area w/ spray foam but it will be a lot more money.  2" thick board would be a good size. I would do as much as you can. Figure out where that air is rushing through and seal it up.

malex

Thanks for all good input

as always. I will definitely try to seal up the crawlspace, probably when it gets a bit warmer so that it is done right and see if that helps. After that an electric heater will go in.